White Wildlife A Fascinating Quirk Of Nature

FOCUS ON NATURE

January 05, 1992|by TOM FEGELY, The Morning Call

Every year reports cross this desk concerning albino birds or mammals spotted somewhere in the Lehigh Valley region.

When I was a teen-ager I recall sighting a white deer in southern Lehigh County. Although no hunter reported killing one during the season and no road kills of white deer were reported, the animal mysteriously disappeared. Within the years following, however, a piebald (partial albino) doe was seen in the same vicinity by several area residents, indicating that the genes of the albino whitetail may have been passed on to another generation.

Since that time I've crossed paths with a photographed more of these unusual quirks of nature, ranging from white whitetails to white robins.

Albinism -- the lack of pigment in an animal or plant -- is not all that rare although it is surely unusual. Reports of albino blackbirds, robins, deer, muskrats and red-tailed hawks have been received in Lehigh County in the past few years.

The best-known albino resident is a redtail that patrols the area near and along Route 33, just south of Wind Gap. Motorists often see the bird perched near the ponds on the east side of the highway or the trees rimming the nearby woods. Another albino redtail has been reported in the Kutztown area, along Route 222, in recent weeks.

Of course, not all white animals are albino. In central New York there's a strain of white white-tailed deer living on an Army post. White birds such as egrets, gulls, swans and domestic ducks have naturally unpigmented feathers but their legs, bills and eyes are colored. Some mammals, like weasels and snowshoe hares, change to white coats during the winter but regain their darker pelage with the arrival of warm weather.

For these animals eons of evolution have equipped them better for their survival during the winter months when they blend into snowy backgrounds. Of course, snowless winters betray their adaptations.

To paraphrase a once-popular song about frogs and their difficulties in being green, it's not easy being white. Not only do these highly-visible creatures stand a better chance of being detected by predators but the lack of color pigment in their eyes also affects their vision, so scientists say. The pink eyes of an albino animal result from the numerous capillaries that remain unmasked by pigment. In turn they take on a shade of the blood's pigment.

Research has shown that a weaker and more uncertain interpretation of an image is caused by this lack of color in the iris.

In addition to birds and mammals, albino salamanders, frogs, insects, snakes, fish and even wildflowers have been documented.

Perhaps the most publicized example of albinism occurs in a town made famous for its populations of albino gray squirrels. Not only is the white squirrel included in the town's promotion information and official seal but policemen of the community -- Olney, Illinois --also wear uniforms with white squirrels emblazoned on their sleeves.

History shows that more than 1,000 resident squirrels, all protected by law, live in Olney. The strain has been traced back to 1892 when a saloon keeper bought a pair of colorless animals and bred them. Since that time the white rodents have been protected but the grays haven't and now the albinos are in the majority.

Other white squirrel populations are known to exist in Greenwood, S.C. where one all-white colony inhabits a 100-acre tract and a larger-than-normal concentration also dwells in Trenton, N.J.

Albinism results from a process that geneticists call "primary mutation." That is, the characteristic is a recessive rather than a dominant trait. Should an albino mate with a normal individual, no albinos will result. However, in the next generation, if interbreeding occurs, albinos may be born. Sometimes albinism remains masked for several generations.

The "original" albino animal is the result of a quirk of nature that accounts for the mutation. When large populations of white animals, like the aforementioned squirrels, are nurtured and protected there's more of a chance for the breeding of pure-white mates and the albinistic gene pool grows.

More common than pure-white animals are partial albinos. Surely every birdwatcher has sighted a blackbird, sparrow or robin with some white tail or wing feathers. Piebald deer, with splotches of brown against white, are also seen each year in parts of the state.

Because of their numbers and their habits of nesting in proximity to one another, the blackbird clan has a high incidence of varied degrees of albinism. One documented study of a flock of Brewer's blackbirds showed that among some 500 individuals, 40 per cent had some white in their plumage.